Video advertisements typically have a greater impact on viewers than traditional online text-based advertisements. Internet users frequently stream online source video for viewing. A search engine may have indexed such a source video. The source video may be a video stream from a live camera, a movie, or any videos accessed over a network. If a source video includes a video advertisement clip (a short video, an animation such as a Flash or GIF, still images, etc.), a human being has typically manually inserted the video advertisement clip into the source video. Manually inserting advertisement video clips into source video is a time-consuming and labor-intensive process that does not take into account the real-time nature of interactive user browsing and playback of online source video.